After months of laughing off Trump — and assuming his ascent would propel the Republican Party to a 1964-style wipeout — her campaign and its allies have begun to steer time and resources into framing lines of attack against the blustery billionaire, even if there’s still considerable confusion over how to attack 2016’s top-of-the-food-chain predator.

“There’s plenty of material out there,” said longtime Clinton confidant James Carville. “We just have to figure it all out.”

With her campaign intensely focused on fending off an unexpectedly strong challenge from Sanders, the man tasked with leading off an eventual anti-Trump offensive is David Brock, the former Clinton foe turned ally who spearheaded the first sharp attacks against the Vermont socialist.

In November, a subsidiary of the Democratic National Committee paid the Brock-run American Bridge $144,000 for “research services,” according to elections filings. That research was devoted almost entirely to building a “Trump Book,” a compendium of clips and other records that could be used for future attacks, a campaign official familiar with the situation told POLITICO. In early December, the Clinton campaign paid the group a further $22,000 for similar work, the official added, and another David Brock-affiliated group, Correct the Record, began a cursory vetting of Trump over the summer.

The emerging approach to defining Trump is an updated iteration of the “Bain Strategy” — the Obama 2012 campaign’s devastating attacks on Mitt Romney’s dealings with investment firm Bain Capital, according to a dozen Democratic operatives and campaign aides familiar with the accelerating planning inside Clinton’s orbit. This time, Democrats would highlight the impact of Trump’s four business bankruptcies — and his opposition to wage hikes at his casinos and residential properties — on the families of his workers.

One Obama ally who helped frame the 2012 Bain strategy added another line of likely attack: “He’s a landlord. Everybody f—ing hates their landlord.”

Hitting Trump on his perceived strength lacks the gut-punch impact of Trump’s recent rehash of Bill Clinton’s sex scandals, but people close to Clinton think the key to beating the real estate mogul is to undermine his oft-repeated assertion that he is a great businessman. And it fits in with Hillary Clinton’s personal philosophy of politics, often articulated to friends and allies, that “attacking an opponent’s strengths,” not their weaknesses, is the key to any presidential campaign.

“Why didn’t the Republicans do this against Trump already? The business stuff is really good fodder,” says veteran Democratic consultant Hilary Rosen, a Clinton supporter who is close to the campaign. “Look, there are real people who have been hurt from his multiple business dealings — real people with real problems. … Those are charges the Republicans were reluctant to make. Democrats won’t make that mistake. Think Bain.”

Those attacks would come in conjunction with a larger, more obvious push by Hispanic and women’s groups to rebroadcast Trump’s greatest, most offensive hits.

Not everyone agrees that Bain-style attacks will dent Trump: One former Obama campaign and White House adviser said that Romney was wounded by the attacks on his business practices because it contradicted his compassionate-conservative pitch to swing voters. “We nailed it because it nailed Mitt on his motivation: He wasn’t this nice guy he claimed to be,” the former staffer said. “Trump never claimed to be nice. … No, the way to attack him is on temperament — a guy like this just isn’t fit to be president.”

Clinton’s team is wary but confident heading into Monday’s caucuses — their internal tracking is consistent with public polling showing her with a slight lead. Sanders’ seemingly unstoppable mid- January momentum has “stalled,” according to one aide. Even with the result uncertain (and Clinton trailing Sanders badly in New Hampshire), the Brooklyn brass — especially campaign chairman John Podesta — think Clinton needs to begin girding immediately for a Trump showdown.

Moreover, there is a growing sense of annoyance on the campaign — especially among Podesta and his one-time boss Bill Clinton — that underestimating Sanders and waiting for the last few weeks to begin attacking his electability and capacity to do the job of president, turned a Clinton romp into a real race. The Clintons don’t want to make the same mistake with Trump, a vastly nastier antagonist than the mildly cranky but intermittently cuddly Vermont socialist.

“Everybody thinks we are sitting around with all these plans, but we haven’t done as much as we should,” said one Clinton insider who speaks to the candidate and her husband regularly.

Trump has confused pundits, reporters, political professionals, his opponents, and not least Clinton and her army of operatives. “The truth is we are as puzzled by this as everybody else, and have no idea what the hell is going to happen with him,” the Clinton insider said. “[Democrats] knew what they were getting in 2008 with McCain; they knew early in 2012 they’d be getting Romney.

You could plan for those guys. You can’t really plan for Trump yet because he’s so unpredictable.”

Clinton’s top advisers, moreover, are still divided over how to deal with him: Initially, she and her team viewed him as a clamorous godsend, an unelectable party-buster who, along with Ted Cruz, would ensure her victory.

To the extent that Clinton could exert any influence on a Republican primary electorate, the candidate’s Brooklyn-based brain trust adopted a strategy of undermining the candidates they believed posed the greatest threat to her among swing voters in a dozen battleground states — mainly Marco Rubio and Jeb Bush, before the latter’s long fade into the slim single digits.

But Trump’s rising appeal with white, working-class voters and his willingness to bring up the ugliest Clinton scandals of the 1990s have unnerved the former first family, according to people in their orbit.

A Clinton-Trump contest would feature two candidates with disapproval ratings traditionally deemed too high for national electoral success: Clinton’s disapprovals hover around the 50 percent range, while Trump’s have rocketed as high as 60 percent, an unprecedented number that should preclude the possibility of his winning a general election.

But attacking him is tougher than it seems, mainly because he is so comfortable throwing a sucker punch and the Clintons aren’t. And he’s already signaled that he would stop at nothing if he faces off against the former secretary of state and her husband.

Late last year, in response to the news that Bill Clinton planned to campaign in New Hampshire, Trump labeled the former president “one of the great abusers of the world” and highlighted charges that he raped an Arkansas woman in the 1970s. Trump also ripped Hillary Clinton’s decision to defend her husband during decades of sex scandals, accusing her of sliming any women who spoke out.

When an interviewer pointed to stories about allegations of abuse by Trump’s first wife, he responded in characteristic hit-me-with-your-best-shot fashion. “You know what? I wasn’t the president of the United States,” he said. “And I wasn’t dealing in the Oval Office, all right? A big difference. I wasn’t the president,” Trump said. “And my first wife thinks I’m great. And my second wife … I have a great marriage. I mean, I have a great marriage. So I mean, it’s fine.”

When NBC’s Chuck Todd asked Trump how he would respond if the Clintons attacked him, he suggested he’d delve more deeply into their personal history.

“Well, I don’t want to say it’s a threat. But it is a threat,” he said on “Meet the Press.”

Even if Trump doesn’t follow through on the threat — or if America yawns — Carville thinks that the Republican front-runner is wily enough to figure out a new way to get under Clinton’s skin.

“Trump’s got talent. He can hold the line when he’s attacked. He uses irony,” he added. “He’s different, so people naturally pay attention. But the question — and nobody can answer it yet — is how he will wear on people over the course of a campaign, over a long period of time? Time may be what really kills Trump.”